Lubricating oil compositions for use in crankcase engine oils include base oils and additives that improve the performance and increase the effective life of the lubricant. Crankcase lubricating oil compositions can contain various polymer components that may be used to improve the viscometric performance of the engine oil.
Polymers are used as viscosity index improvers and often comprise copolymers of ethylene and propylene, among others. A challenge for oil formulators is to find polymers that may both improve high temperature viscosity performance as well as improve low temperature performance such as cold engine starting performance. These attributes, among others, can cause performance tradeoffs with respect to given polymer additives wherein an improvement in one way can be offset by reduced performance in another. Additionally, there is always a commercial incentive to have the polymer be effective at the lowest reasonable concentrations in order to minimize the cost of a given engine oil product or additive.